Inflatable air cell dunnage

ABSTRACT

Air cell dunnage is disclosed which collapses for shipment and is constructed to be subsequently inflated for use. The air cell dunnage is a bubble sheet containing a multiplicity of gas cells and a base layer fused to the bubble layer. The bubble layer further includes conduits interconnecting selected groups of the selected cells and a common channel extending longitudinally on the sheet in fluid communication with each of the selected groups. The conduits provide access to selected groups of gas cells for collapsing and inflating the cells for shipment and use, respectively.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a division of pending U.S. patent applicationSer. No. 09/296,363 filed Apr. 22, 1999, the specification of which ishereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] This invention relates to air cell dunnage and, moreparticularly, to air cell dunnage which is intended to be inflated atthe time of use.

[0003] Air cell dunnage is typically used for shipping products whichmay be subject to breakage. The dunnage may be wrapped around theproduct or stuffed into a container to prevent movement of the productwithin the container during shipment and to protect against shock.

[0004] Conventionally, manufacturing air cell dunnage involves vacuumforming a multiplicity of bubbles to form a bubble layer. The bubblesare separated by flats which are bonded (thermally) to a flat base layerto form a bubble sheet in which air is trapped within the hemisphericalvacuum formed bubble. This bubble sheet or air cell dunnage as it iscommonly known, is shipped in this form to end users who use the dunnageto package their products for shipment.

[0005] The manufactured bubble sheet is relatively bulky, being close to100 times the thickness of the combined thickness of the plastic filmfrom which the bubble sheet is manufactured. Obviously, this bulkincreases the cost of shipping of the manufactured air cell dunnage tothe ultimate end user.

[0006] Moreover, the manufacture of the bubble sheet takes place atrelatively high temperature (for example, about 120 E c). After the baselayer is fused to the bubble layer, the temperature of the bubble sheetdrops to room temperature which is approximately 20 E c. Because of thisdrop in temperature, the volume of the air within the individual bubblesor cells decreases by about 25%. Using these figures, this would meanthat only about 75% of the available volume of a bubble is being used.It can be shown that when 75% of the available volume of a bubble isused, the height of the bubble is only 56% of the height of a fullyinflated bubble. This means that if the individual bubbles could beexpanded to their full size, the bulkiness (thickness) of the productwould be almost doubled. Conversely, to achieve the bulkiness of a priorart bubble sheet in which the bubbles are only expanded to 75% of theirvolume, a fully expanded bubble sheet would require 44% less rawmaterial. Thus, it is desirable to increase the percentage of theavailable volume of the bubbles which is filled with air.

[0007] The main object of this invention is to provide air cell dunnagewhich can be inflated by the end user, which means that the manufacturedproduct is much less bulky than before and which also enables theindividual bubbles to be filled with a greater volume of air.

[0008] A further object of the invention is to provide air cell dunnagein which less material is required for a specified amount of bulkiness.

SUMMARY OF THE INVENTION

[0009] In accordance with the invention, the individual cells of abubble sheet are interconnected by a series of conduits which lead toatmosphere. When the bubble layer is fused to the base layer, theconduits function as a vent so that the fused bubble sheet can beflattened to evacuate the air within the bubble sheet. The flattenedbubble sheet is shipped to the end user.

[0010] The end user inflates the bubble sheets by connecting theconduits to an air supply. This will take place at room temperaturewhich means that the individual cells or bubbles can be completelyfilled with air. After the bubble sheet has been inflated, theindividual conduit(s) are sealed so that the captured air is retainedwithin the bubble sheet which can then be used in conventional fashion.

BRIEF DESCRIPTION OF DRAWINGS

[0011]FIG. 1 is a plan view of a bubble sheet in accordance with apreferred embodiment of the invention; FIG. 2 is a plan view of a bubblesheet showing a preferred mechanism for expelling air from the bubbles;FIG. 3 is a side sectional view along the line 3-3 of FIG. 1; FIG. 4 isa side sectional view along the line 4-4 of FIG. 2; FIG. 5 is a planview showing schematically how the bubbles are inflated and, theconduits sealed; and FIG. 6 is a side sectional view along the line 6-6of FIG. 5.

DETAILED DESCRIPTION

[0012]FIG. 1 shows a bubble layer 10 in accordance with the inventionafter vacuum forming. A multiplicity of bubbles 12 are typically formedin a diagonal pattern which maximizes the number of bubbles in a givenarea. In accordance with the invention, in each “diagonal” row, thebubbles 12 are interconnected by means of conduits 14. On one side ofthe sheet, i.e, the right hand side illustrated in FIG. 1, the conduits14 lead to a channel 15 at the edge of the bubble layer 10. Channel 15can be used as an exhaust channel for deflating the bubbles and theconduits, and it can be accessed by the end user for the purpose ofinflating the bubble sheet as described below.

[0013] For purposes of explanation, the interconnected bubbles in asingle row have been labeled in FIG. 1 with the letters A through Z,respectively, with the right hand bubbles indicated by the subscript 1and the bubble in the left hand position of the same row by thesubscript 5. For example, a single diagonal row of interconnectingbubbles, contains bubbles A₁ through A₅. Typically, the sheet 10 will beabout 1.5 meters wide which means that a single diagonal row of bubblesmay contain as many as sixty bubbles. The drawings are not intended toillustrate an actual bubble sheet but represent instead a schematicexample for purposes of explanation.

[0014] By way of example only, if the bubbles 12 are formed as one inchhemispheres, the conduits 14 may be semi-cylindrical forms about ⅛ inchin diameter and channel 15 about ¼ inch in diameter. They would also bevacuumed formed during the process of manufacturing the bubble layer.This would mean that the roller which contains the female hemisphericaldies for forming the bubbles would also include comparable femalesemi-cylindrical dies for forming the conduits 14 and channel 15. It isalso contemplated that the conduits 14 and channel 15 may be formed inthe base layer 16, either in whole or in part.

[0015] After the bubble layer shown in FIG. 1 has been formed, it isjoined to a base layer 16 in conventional fashion to form a bubble sheet(FIGS. 2 and 3). The base layer 16 contacts the bubble layer only inthose regions which are “flat”, i.e. the regions outside of the bubbles12, conduits 14 and channel 15. Typically, layers 10 and 16 arethermally fused together.

[0016] In accordance with the invention, after the bubble sheet has beenformed, the bubbles are deflated so that the sheet can be shipped in aflattened condition. For this purpose, as shown in FIGS. 2 and 4, a pairof nip rollers 18 and 20 are provided. The axes of the nip rollers 18and 20 are arrayed as shown in FIG. 2 so that they are perpendicular tothe conduits 14 of each diagonal row of bubbles A, B, C, etc. The niprollers 18 and 20 rotate in the direction of the arrows causing air tobe expelled from each row of bubbles through the side channel 15 toatmosphere. Assuming that the bubble sheet moves in the direction ofarrow 22 as it is produced, the bubbles shown to the left of the niprollers 18 and 20 will be flattened and the bubbles on the right handside will still contain air. It is desirable for the nip rollers 18 and20 to be transverse to the conduits 14 to make sure that all of the airin a given bubble is expelled by the nip rollers. If the nip rollerswere not transversed to conduits 14, air could be trapped within theindividual bubbles. The nip rollers 18 and 20 do not function to movethe bubble sheet and provide only negligible resistance to the movementof the bubble sheet as it is produced.

[0017] The flattened bubble sheet, as indicated above, may beapproximately 100 times thinner than the inflated bubble sheet. Becauseof this enormous reduction in bulk, the cost of transporting and storingthe bubble sheet is greatly reduced.

[0018] After the deflated bubble sheet has been shipped, it is necessaryto inflate the bubble sheet so that it can be used. For this purpose,apparatus of the type shown schematically in FIG. 5 can be employed. Theapparatus includes a nozzle 30 having an exterior blade 32 whichincludes a cutting edge 34, and a heat sealing arrangement whichincludes two rollers 36 and 38 (FIG. 6). As shown the nozzle 30 istapered with its wider portion sealing the channel 15 so that air fromthe nozzle cannot escape.

[0019] The flattened bubble sheet typically will be shipped in the formof a large roll as shown at the bottom of FIG. 5 at 39 and will beunwound in the direction of arrow 40 using conventional rollers (notshown). The nozzle 30 is inserted into the leading edge of channel 15.Nozzle 30 provides air under pressure which inflates each of thediagonally interconnected rows of bubbles A, B, C, etc. as the bubblesheet is unrolled. The heat sealing process requires the application ofheat and pressure to the plastic bubble sheet in the areas of theconduits 14. For this purpose, the upper roller 36 may include amultiplicity of cavities 42 which conform generally to the shapes of theindividual air bubbles. The lower roller 38, on the other hand, may becylindrical in shape with heating wires embedded in the surface of thecylinder to raise the temperature of the plastic sheet to a temperatureat which fusion will occur under the pressure applied by the tworollers. The heating wire will trace a path as shown by the dotted lines44 which ensures that the high temperature is not applied directly tothe bubbles and also that the seal at the conduits 14 is generallytransverse to the individual conduits.

[0020] The heat sealing rollers 36 and 38 are arranged to seal thebubbles after an entire diagonal row has been inflated. For example, asshown in FIG. 5, the heat sealing rollers must not seal the conduit 14between bubble E₁ and channel 15 until all of the bubbles E₁-E₅ havebeen inflated because after that seal has been made, it is no longerpossible to provide air to the remaining bubbles in the diagonal linewhich has been sealed. After the conduit 14 between bubble E₁ andchannel 15 is sealed, as the sheet continues to move in the direction ofarrow 40, the conduit 14 between bubbles E₁ and E₂ is sealed and soforth until finally the conduit between bubble E₄ and E₅ is sealed. Atthis point, each of the bubbles E₁-E₅ is independent of the remainingbubbles.

[0021] The same procedure, of course, applies to each successivediagonal row of bubbles. When the leading bubble of each row, e.g.bubble C₁, reaches the blade 32, cutting edge 34 cuts the channel 15 sothat the inflated bubble sheet can be separated from the nozzle 30 foruse in conventional fashion. Because the nozzle 30 fits tightly withinthe channel 15 it is still possible to expand the bubbles through theunsevered portion of channel 15 below the outlet of nozzle 30.

[0022] Other arrangements of the conduits can be shown in addition towhat is illustrated in FIGS. 1 and 2. It is not necessary that eachdiagonal row of bubbles be separately inflatable and any practicalnumber of diagonal rows may be interconnected so that they can besimultaneously inflated.

1. A device for inflating collapsed air cell dunnage including aflattened bubble sheet having a bubble layer, a base layer connectedthereto and gas expelled from the bubbles in the bubble sheet, thebubble layer further including conduits interconnecting selected groupsof bubbles and a common channel extending longitudinally on the sheetand in fluid communication with each of the groups through the conduits,comprising: a nozzle including an exterior blade with a cutting edge,the nozzle being inserted into the leading edge of the channel in orderto introduce gas under pressure into the channel; a heat sealing deviceincluding two rollers constructed to seal the conduits in between thebubbles in the selected groups after the bubbles have been inflated; andthe exterior blade adapted to cut the channel so that the inflated aircell dunnage can be separated from the nozzle for use.
 2. A method forinflating collapsed air cell dunnage including a flattened bubble sheethaving a bubble layer, a base layer connected thereto and gas expelledfrom the bubbles in the bubble sheet, the bubble layer further includingconduits interconnecting selected groups of bubbles and a common channelextending longitudinally on the sheet and in fluid communication witheach of the groups through the conduits, comprising: inserting a nozzleinto the leading edge of the channel in order to introduce gas underpressure into the channel; sealing the conduits in between the bubblesafter the bubbles have been inflated; and cutting the channel so thatthe inflated air cell dunnage can be separated from the nozzle for use.